Large volumes of concrete have the potential to
experience temperature gradients because of heat released during curing that
can lead to cracking. Cracking of mass concrete in coastal structures is of
special concern because of its exposure to saltwater with its corrosive effects
on steel reinforcement. A finite element
model was developed to predict the temperature rise and temperature
distributions arising from early age concrete hydration, as well as the
stresses induced by the resulting temperature gradients. The model was
validated by a laboratory experiment and used to analyze several mass concrete
footings in bridges in the coastal region of North Carolina for their early age
thermal cracking potential. Reasonably
sized mass concrete structures that followed the typical NCDOT control plans
did not have a high likelihood of significant cracking from thermal stresses,
while large mass concrete footings have a much higher risk of significant
cracking even when the typical NCDOT control plans are followed. Based this research and other studies in the
literature, additions and revisions to current NCDOT mass concrete
specifications were recommended.
